1. Technical Field
The present invention generally relates to packaging solutions for ophthalmic devices such as contact lenses.
2. Description of Related Art
Blister-packs and glass vials are typically used to individually package each soft contact lens for sale to a customer. Saline or deionized water is commonly used to store the lens in the blister-packs, as mentioned in various patents related to the packaging or manufacturing of contact lenses. Because lens material may tend to stick to itself and to the lens package, packaging solutions for blister-packs have sometimes been formulated to reduce or eliminate lens folding and sticking. For this reason, polyvinyl alcohol (PVA) has been used in contact-lens packaging solutions.
It has been stated that if a lens is thoroughly cleaned before insertion, lacrimal fluid can adequately wet the lens. Furthermore, the difficulties of adding a surfactant to a packaging solution, including the possibility of lowering shelf-life and/or adverse reactions during heat sterilization, have further limited the use of surfactants in a packaging solution for the purpose of providing any possible or marginal effect on lens comfort. It is only after a lens has been worn, when proteins or other deposits have formed on the surface of the lens, that surfactants have been used in standard lens-care solutions.
It is highly desirable that a contact lens be as comfortable as possible for wearers. Manufacturers of contact lenses are continually working to improve the comfort of the lenses. Nevertheless, many people who wear contact lenses still experience dryness or eye irritation throughout the day and particularly towards the end of the day. An insufficiently wetted lens at any point in time will cause significant discomfort to the lens wearer. Although wetting drops can be used as needed to alleviate such discomfort, it would certainly be desirable if such discomfort did not arise in the first place.
U.S. Pat. No. 6,440,366 (“the '366 patent”) discloses a package containing a contact lens suitable for immediate use which comprises (a) a solution comprising a non-ionic surfactant that is a compound comprising at least 90 weight percent of poly(oxyethylene) and poly(oxypropylene) segments, in one or more block copolymer chains, and (b) an effective amount of a tonicity adjusting agent such that the solution has an osmolality of 200 to 400 mOsm/kg; wherein the solution has a pH of about 6 to 8 and is heat sterilized and lacks an effective disinfecting amount of a disinfecting agent. The '366 patent further discloses that the surfactant is a poly(oxypropylene)-poly(oxyethylene) adduct of ethylene diamine.
It would be desirable to provide an improved packaging system for ophthalmic devices such as a contact lens such that the lens would be comfortable to wear in actual use following its removal from the packaging system and allow for extended wear of the lens without irritation or other adverse effects to the cornea.